Coccidiosis, a poultry disease, is caused by several species of protozoan parasites of the genus Eimeria such as I. necatrix, E. acervuliana, E. maxima, E. hagani, E. tenella. E. tenella is the causative agent of a severe and often fatal infection of the ceca of chickens which is manifested by extensive hemorrhage, accummulation of blood in the ceca and the passage of blood in the droppings. Essentially, coccidiosis is an intestinal disease which is disseminated by birds picking up the infectious organism in droppings on contaminated litter or ground. By damaging the intestinal wall, the host animal is unable to utilize its food, goes off its feed, and in untreated cases the disease terminates in either the death of the animal or the survival of unthrifty birds known commonly as "culls".
Much work has been done in this area in developing compounds having anticoccidial activity. For instance, there are effective compounds such as sulfur, sulfa drugs, arsenicals, dihydro-1,3-5-triazines (U.S. Pat. No. 2,823,161); 3-amino-as-triazine complexes with substituted ureas (U.S. Pat. No. 2,731,385); 1-phenyl-3-(3-as-triazinyl) ureas (U.S. Pat. No. 2,762,743); 5-fluorouracil (U.S. Pat. No. 3,017,322); and as-triazine-3,5-(2H,4H) dione (U.S. Pat. No. 2,956,924). Another effective group of compounds for controlling and treating coccidiosis is the substituted bis-thiosemicarbazones of cyclic 1,2-diketones and metal chelates which are the subject of U.S. Pat. Nos. 3,382,266 and 3,622,674. Also found to be effective are the 6-azauracils as disclosed and claimed in my pending CIP patent applications Ser. Nos. 364,672 filed May 29, 1973 (U.S. Pat. No. 3,905,971) and 381,062 filed July 20, 1973 (U.S. Pat. No. 3,912,723).